1. The Field of the Invention
This invention relates to tube couplings which may be single or multiple tube couplings providing inline, elbow or T-couplings or tube closures.
2. The Relevant Technology
Our “Speedfit” tube connector (the subject of UK Patent No. 1520742) has a coupling body with a throughway open at one end and a tapered cam surface in the open end to receive a collet for locking a tube in the coupling. The collet is compressed against the tube by a slight withdrawal of the tube and collet from the coupling body which locks the tube in the coupling body. The collet can be depressed into the body to release the tube.
Our “Superseal” connector (the subject of our UK Patent No. 2167147) has a separate sleeve screwed onto the open end of the coupling body in which the tapered cam is formed. By screwing the sleeve onto the coupling body the gripping action of the collet on the tube is increased. Also the collet becomes locked up in the coupling body and cannot be depressed to release the tube.
Our “Speedfit/Superseal” coupling (the subject of European Patent Publication No. 0945662) comprises a coupling body having a throughway open at one end to receive an end portion of a tube and having an internal cam surface tapering towards the open end in which a collet is located for locking the tube in the coupling body by engagement with the tapered cam surface, and having step means to limit entry of the collet into the throughway, the coupling body having a main body the throughway of which receives the end of a tube and contains said step means to limit insertion of the collet and an end cap in screw threaded engagement with the main body containing said open end to the throughway and the tapered cam surface, and indexing means between the end cap and main body to define different positions of rotational adjustment in the first of which a tube can be inserted and, by depressing the collet into the coupling body, released from the coupling body and in the second of which the collet is engaged with the step means to prevent the collet being depressed into the coupling body to release the tube. In the preferred arrangement the end cap has an internally threaded sleeve portion encircling and in screw threaded engagement with an external thread on the main body.
In the latter construction, an “O” ring seal is provided in the throughway in the coupling body to engage and seal with the outer surface of the tube. The seal is spaced from the ends of the collet by a washer or sleeve. This arrangement provides small cavities between adjacent components in which liquids can penetrate and become trapped and difficult to remove by cleaning. Such entrapped liquids can deteriorate over a period of time and cause contamination in subsequent liquid flowing through the coupling.
Our European Patent Publication No. 1233225 discloses a tube coupling to receive and hold a tube comprising a coupling body having a throughway open at one end to receive a tube, an annular step in the throughway facing the open end to receive an end of a tube, an end cap engaging the coupling body for axial movement between forward and retracted position on the coupling body, the end cap having an opening for the tube to extended through, a seal located in the coupling body between the step and the open end of the body and in the form of an annular sleeve encircling the throughway, the seal having an out turned annular flange at one end which engages with the annular step to receive and seal with an end of the tube inserted into the throughway and means operable by the end cap to compress the sleeve around the outer surface of the tube adjacent said end of the tube to from a seal with the end of the tube.
This arrangement provides a combination of the “Speedfit” and “Superseal” features referred to above in which any potential leak paths from an end of a tube in the coupling body is minimised and recesses or cavities between adjacent components in the leak path are minimised to present a substantially clean, smooth internal surface to the outer side of the tube connected in the coupling.
The latter arrangement is, however, relatively complicated requiring inter fitting components which present some manufacturing difficulties particularly for small sizes of tube couplings.